A089327 Smallest prime p such that 10*n*p +1 is prime.

3, 2, 2, 7, 2, 3, 3, 3, 2, 7, 3, 2, 7, 2, 5, 13, 11, 3, 3, 2, 2, 3, 2, 5, 3, 2, 2, 31, 5, 2, 37, 2, 2, 3, 2, 5, 7, 2, 3, 3, 2, 11, 3, 2, 5, 3, 2, 7, 3, 11, 2, 13, 2, 3, 7, 5, 5, 3, 2, 2, 3, 3, 13, 7, 2, 2, 3, 2, 2, 31, 3, 3, 13, 2, 3, 3, 3, 3, 3, 2, 2, 7, 29, 3, 3, 2, 2, 31, 3, 2, 3, 17, 2, 7, 2, 5, 7, 11

Offset

1,1

Links

Table of n, a(n) for n=1..98.

Example

31,41,61,281, etc. are primes.

Mathematica

With[{prs=Prime[Range[100]]}, Table[SelectFirst[prs, PrimeQ[10n*#+1]&], {n, 100}]] (* The program uses the SelectFirst function from Mathematica version 10 *) (* Harvey P. Dale, Apr 27 2015 *)

Crossrefs

Sequence in context: A299778 A302248 A235773 * A280851 A279391 A237270

Adjacent sequences: A089324 A089325 A089326 * A089328 A089329 A089330

Keyword

base,nonn

Author

Amarnath Murthy, Nov 03 2003

Extensions

More terms from David Wasserman, Sep 13 2005

Status

approved